JP4726605B2 - Liquid crystal display device and optical sheet mounting method - Google Patents

Description

  The present invention relates to a liquid crystal display device and an optical sheet mounting method, and more particularly to a liquid crystal display device having a large screen size and an optical sheet mounting method suitable for the liquid crystal display device.

  Liquid crystal display devices are characterized by their small size, thinness, and low power consumption. In recent years, liquid crystal display devices have become widespread as displays replacing conventional CRTs due to their improved display quality. Unlike a self-luminous device, a liquid crystal display device requires a backlight as a light source, and displays an image by controlling light transmittance determined by the electro-optical characteristics of the liquid crystal material.

  In the liquid crystal display device, the display quality is improved by providing an optical sheet in the gap between the liquid crystal panel and the backlight. As a method for holding the optical sheet, Patent Document 1 discloses a fastener that can position and fix the planar light emitting element or the light guide and the optical sheet without using the double-sided tape. An illuminating device and a liquid crystal display device using the above are disclosed.

  Further, in Patent Document 2, an optical sheet is held by a sticking head in a state where a laminated body in which an optical sheet, an adhesive layer, and a release sheet are laminated in this order is elastically supported at a release sheet peeling position. An optical sheet affixing method and an apparatus for affixing an optical sheet accurately at a predetermined position by absorbing thickness variation of the sheet by elastic support are disclosed.

By the way, in the liquid crystal display device, there is a problem that the optical sheet is bent by the heat from the backlight and uneven brightness occurs. Therefore, as shown in FIG. 6, a cold cathode ray discharge tube (CCFL) 140 is formed on the bottom surface of a rectangular parallelepiped box (backlight chassis) 121 having a reflection film 122 formed on the inner wall and opened on the front surface via a clip 141. Is fixed to the backlight chassis 121 with screws 128, the molding spring 126 presses the optical sheet 130, and the optical sheet is backlit. A technique for attaching to the light-emitting side has been devised.
Japanese Patent Laid-Open No. 2004-233383 JP 2004-86075 A

  However, in the optical sheet attaching method shown in FIG. 6, the forming spring 126 is necessary, and the forming spring 126 needs to be attached to the tip of the fixture 125. Therefore, the number of parts is increased and the forming spring 126 is adjusted with accuracy. There was a problem that it was necessary to attach well and the cost was unavoidable. In addition, when there is variation in the mounting of the molding spring 126, an intrusion path such as external dust and chalk is generated between the optical sheet 130 and the backlight chassis 121, and the intruded dust adheres to the surface of the CCFL 140. As a result, the emission intensity may be reduced.

  The present invention has been made in view of such circumstances, and an optical sheet having a peripheral portion bent toward the backlight side is disposed so as to contact the surface of the backlight, and a portion inside the bent peripheral portion is disposed. An optical sheet mounting method capable of stably mounting an optical sheet with an extremely low-cost configuration by pressing the fixture with the fixture and fixing the fixture to the peripheral edge of the backlight to maintain the pressed state. Another object is to provide a liquid crystal display device.

  Further, the present invention is configured such that the front end portion of the frame-shaped fixture corresponding to the peripheral edge portion of the optical sheet is bent toward the backlight side, and the front end portion presses a portion inside the peripheral edge portion of the optical sheet. Accordingly, an object of the present invention is to provide a liquid crystal display device capable of stably and efficiently pressing an optical sheet with an appropriate strength.

  Further, according to the present invention, as a backlight base, a groove is provided on the opening side edge of the two opposite side walls of the rectangular parallelepiped box having an opening on the liquid crystal panel side, and the front end of the fixture in the frame outer direction is grooved. It is an object of the present invention to provide a liquid crystal display device capable of performing the alignment of the fixture with respect to the backlight and performing the position regulation between the fixture and the backlight with high accuracy.

  The liquid crystal display device according to the present invention is a liquid crystal display device comprising a liquid crystal panel and a backlight having one or more light sources on the back surface of the liquid crystal panel, provided in a gap between the liquid crystal panel and the backlight, An optical sheet whose portion is bent toward the backlight side, and a fixture that presses a portion inside the peripheral portion of the bent optical sheet and is fixed to the peripheral portion of the backlight. To do.

  In the present invention, the optical sheet whose peripheral part is bent toward the backlight side is provided in the gap between the liquid crystal panel and the backlight, and the part inside the peripheral part of the bent optical sheet is pressed by the fixture. The fixture is fixed to the peripheral edge of the backlight. Thereby, the restoring force which tries to restore | restore the deformation | transformation which arose by the press generate | occur | produces in an optical sheet, and the produced restoring force acts on a fixing tool, and can fix the position of an optical sheet stably. In addition, a molding spring is not required as compared with the conventional case, and the optical sheet can be attached with a very low cost configuration. In addition, since the optical sheet is pressed to the backlight side by the fixture, there is no gap between the optical sheet and the backlight, and external dust and chalk do not enter the light source space. Therefore, the light emission intensity is not reduced due to dust adhering to the surface of the light source.

  In the liquid crystal display device according to the present invention, the fixing member has a frame shape corresponding to a peripheral edge portion of the optical sheet, the front end portion in the frame inner direction is bent toward the backlight side, and the front end portion is the optical sheet. It is characterized by pressing a portion inside the peripheral edge of the.

  In the present invention, the front end portion of the frame-shaped fixture corresponding to the peripheral edge portion of the optical sheet is bent toward the backlight side and presses the portion inside the peripheral edge portion of the optical sheet. . As a result, the optical sheet can be pressed and fixed stably and efficiently with an appropriate strength. The force acting on the optical sheet is weak, and even when the optical sheet is thermally expanded, the position of the optical sheet in contact with the front end of the fixture in the frame direction moves, and the optical sheet is wrinkled. Will not occur.

  In the liquid crystal display device according to the present invention, the light source is provided in a rectangular parallelepiped box having an opening on the liquid crystal panel side and having a groove on an edge portion on the opening side of two opposing side walls, The front end portion in the frame outer side direction is bent toward the backlight side, and the front end portion is fitted into the groove.

  In the present invention, a groove is provided at the edge of the opening side of the two opposite side walls of the rectangular parallelepiped box having the liquid crystal panel opened as the base of the backlight, and the distal end of the fixture in the frame outer direction Is inserted into the groove. Thereby, position control with a fixture and a backlight can be performed with high precision. Since the position can be regulated by fitting the distal end of the fixture in the frame outer direction into the groove, there is no variation during the assembly process.

  The optical sheet mounting method according to the present invention is an optical sheet mounting method in which an optical sheet is mounted on a surface of a backlight having one or a plurality of light sources by using a fixture, and a peripheral portion of the optical sheet is bent and bent. The optical sheet is disposed so that the peripheral edge is in contact with the surface of the backlight, the inner part of the bent optical sheet is pressed with the fixing tool, and the fixed tool is held so as to hold the pressed state. Is fixed to the backlight.

  In the present invention, the optical sheet is disposed such that the peripheral edge of the optical sheet is bent and the bent peripheral edge is in contact with the surface of the backlight. And the part inside the peripheral part of the bent optical sheet is pressed with a fixing tool, and the fixing tool is fixed to the backlight to hold the pressed state. Thereby, the restoring force which tries to restore | restore the deformation | transformation which arose by the press generate | occur | produces in an optical sheet, the produced restoring force acts on a fixing tool, and can fix the position of an optical sheet stably. In addition, the optical sheet can be arranged with high accuracy by an extremely simple process as compared with the prior art.

  According to the present invention, the optical sheet whose peripheral part is bent toward the backlight side is arranged so as to be in contact with the surface of the backlight, and the inner part of the bent peripheral part is pressed by the fixing tool and pressed. By fixing the fixture to the peripheral edge of the backlight so as to maintain the state, the optical sheet can be stably attached with a configuration that is extremely low in cost compared to the conventional art.

  According to the present invention, the front end portion of the frame-shaped fixture corresponding to the peripheral edge portion of the optical sheet is bent toward the backlight side, and the front end portion presses the portion inside the peripheral edge portion of the optical sheet. Since it was set as the structure, an optical sheet can be pressed stably and efficiently with moderate intensity | strength.

  According to the present invention, as the base of the backlight, a groove is provided in the opening side edge portion of the two opposite side walls of the rectangular parallelepiped box that is open on the liquid crystal panel side, and the front end of the fixture in the frame outer direction is provided. Since it is configured to be inserted into the groove, an excellent effect is achieved such that alignment of the fixture with respect to the backlight can be performed and position control between the fixture and the backlight can be performed with high accuracy.

  Hereinafter, the present invention will be described in detail with reference to the drawings illustrating embodiments thereof.

  FIG. 1 is a perspective view showing an external appearance of a liquid crystal display device according to the present invention, and FIG. 2 is a cross-sectional view showing an internal configuration of the liquid crystal display device according to the present invention.

  The liquid crystal display device according to the present invention includes a liquid crystal panel 10 and a backlight 20 provided on the back side of the liquid crystal panel 10, and the liquid crystal panel 10 and the backlight 20 are formed by a front cabinet 51 and a back cabinet 52. It is arranged in the space. The front cabinet 51 is provided with an opening 51a, and an image of the liquid crystal panel 10 is displayed through the opening 51a. The liquid crystal panel 10 and the backlight 20 are fixed to a support frame (not shown) having dimensions that match the outer dimensions of the liquid crystal panel 10. Two support columns extending in the vertical direction are fixed to the support frame so as to connect two sides facing the upper and lower sides of the support frame, and a stand 60 is attached to the support frame.

  The liquid crystal panel 10 has a configuration in which a pair of transparent plates 11 and 12 are arranged to face each other, and a liquid crystal substance 14 is filled in a gap formed by sealing the periphery of the transparent plates 11 and 12 with a sealing material 13 or the like. ing. Of course, it is preferable to hold the liquid crystal gap with high accuracy using a spherical or columnar spacer. One transparent plate 11 is formed with a transparent pixel electrode such as ITO or NESA arranged in a matrix and a TFT for controlling the supply of electric charges to the pixel electrode. A transparent common electrode called a common electrode is formed in the. The gate and source of the TFT are connected to the output stages of the gate driver and source driver, respectively.

  Two polarizing plates 15 and 16 whose polarization axes are orthogonal to each other are attached to the surfaces of the transparent plates 11 and 12, respectively, and on / off of each pixel electrode is controlled by a gate signal input from a gate driver. By applying the data signal input from the source driver to each pixel electrode during the on-period, the voltage of the liquid crystal substance 14 is determined based on the voltage difference between the voltage applied to the pixel electrode and the voltage applied to the counter electrode. Control light transmission.

  In the liquid crystal panel 10 as described above, the front and back peripheral portions of the liquid crystal panel 10 are sandwiched between two sandwiching members 71 and 72, and one sandwiching member 72 is fixed to the backlight 20 with screws 57. Thereby, the relative position of the liquid crystal panel 10 and the backlight 20 does not fluctuate.

  The backlight 20 has a rectangular parallelepiped box (backlight chassis) 21 whose front surface is opened as a base, and a reflective film 22 is formed on the inner wall of the backlight chassis 21. The reflective film 22 is formed by evaporating a material having excellent light reflectivity such as aluminum.

  In addition, a plurality of linear cold cathode ray discharge tubes (CCFL) 40 as light sources are juxtaposed in the vertical direction in a horizontal state, and white light close to natural light enters the liquid crystal panel 10 provided on the front surface. ing. In this example, the CCFL 40 is fixed to the bottom surface of the backlight chassis 21 by a clip 41 known per se provided at an appropriate position. In addition, you may use what arrange | positioned white LED and / or LED of multiple colors as a backlight.

  A fixing tool 25 that functions as a frame having a U-shaped cross section is attached to the backlight chassis 21 at the peripheral edge of the backlight chassis 21 with screws 28. The distal end portion 25 b of the fixture 25 in the frame outer direction is fitted into a groove 27 provided in the peripheral portion of the backlight chassis 21, and regulates the positions of the fixture 25 and the backlight chassis 21. The distal end portion 25 a of the fixture 25 in the frame inner direction presses the inner portion of the edge of the optical sheet 30.

  The optical sheet 30 is a laminated body such as a diffusion plate, a diffusion sheet, R-BAF, and D-BAF. The optical sheet 30 has a rectangular shape with an aspect ratio of 4: 3 (or 16: 9) and is sandwiched between the fixture 25 and the backlight chassis 21 in a state in which the peripheral edge is bent in a “<” shape. Has been. Since the optical sheet 30 bent in a “<” shape has a spring property, the optical sheet 30 can be stably pressed to the backlight chassis 21 with an appropriate strength.

  In addition, since the tip of the optical sheet 30 is pressed toward the backlight chassis 21 by the fixture 25, there is no gap between the tip of the optical sheet 30 and the backlight chassis 21. Therefore, since external dust, chalk, and the like do not enter the space where the CCFL 40 is juxtaposed, the emission intensity is not reduced due to dust adhering to the CCFL 40 surface.

  FIG. 3 is a diagram showing a state of the optical sheet in the liquid crystal display device according to the present invention during thermal expansion. FIG. 3A shows a state before the backlight is used, that is, before the CCFL 40 is turned on. Indicates a state in which the backlight is in use, that is, the CCFL 40 is lit.

  Since the optical sheet 30 is provided at a position where the distance from the CCFL 40 is about several centimeters, the optical sheet 30 ′ is affected by the heat generated by the lighting of the CCFL 40 (indicated by a wavy line in FIG. 3). Thermal expansion. Since the position of the optical sheet is held by the spring property of the optical sheet itself, the force acting on the optical sheet is weak. Therefore, when the optical sheet is thermally expanded, the position of the optical sheet in contact with the distal end portion 25a in the frame inner direction of the fixture 25 is moved from X1 to X2, so that the optical sheet is not wrinkled.

FIG. 4 is an explanatory view showing an optical sheet mounting method according to the present invention.
First, the peripheral portion of the optical sheet 30 is bent, and the optical sheet 30 is disposed on the light emission surface side of the backlight chassis 21 (FIG. 4A). Here, the case where the peripheral portion of the optical sheet 30 is bent by 60 degrees is shown, but the bent shape is appropriately determined depending on the outer dimensions, strength, temperature characteristics, and the like of the optical sheet.

  Next, the fixture 25 is disposed on the peripheral portion of the backlight chassis 21 in a state where the front end portion 25b of the fixture 25 in the frame outer side direction is fitted in the groove 27 provided on the peripheral portion of the backlight chassis 21 (FIG. 4 (b)). This step is a step of aligning the fixture 25 with respect to the backlight chassis 21, and the front end portion 25 a of the fixture 25 in the frame inner direction comes into contact with a portion inside the peripheral portion of the optical sheet 30. At this time, no force acts on the peripheral edge of the optical sheet 30 from the fixture 25.

  And the fixing tool 25 is fixed to the peripheral part of the backlight chassis 21 using the screw | thread 28 (FIG.4 (c)). By screwing the screws 28, the distal end portion 25 a of the fixture 25 in the frame inner direction presses a portion inside the peripheral edge portion of the optical sheet 30, and the optical sheet 30 is bent into a “<” shape. When the optical sheet 30 is pressed, the optical sheet 30 is deformed, and a restoring force for restoring the deformation is generated in the optical sheet 30. This restoring force acts on the distal end portion 25 a of the fixture 25, and the optical sheet 30 is sandwiched between the fixture 25 and the backlight chassis 21.

  As described in detail above, the gist of the present invention is to attach the optical sheet 30 with an appropriate strength by utilizing the spring property generated by bending the optical sheet 30. Thereby, compared with the thing of the conventional structure shown in FIG. 6, a shaping | molding spring becomes unnecessary and the optical sheet 30 can be attached by a very low-cost structure. Further, since the optical sheet 30 is pressed against the backlight chassis 21 by the fixture 25, an intrusion path into the light source space such as dust and chalk occurs between the optical sheet 30 and the backlight chassis 21. In other words, it is possible to prevent dust from adhering to the surface of the light source.

  In this embodiment, the direct type backlight 20 in which a plurality of CCFLs 40 as light sources are juxtaposed has been described. However, the backlight type such as a side type backlight is not limited, and a liquid crystal panel and The present invention can be applied to the case where an optical sheet is provided in the gap of the backlight.

  For example, as shown in FIG. 5, the CCFL 40 is disposed on the side of the backlight chassis 21, and the light emitted from the CCFL 40 is emitted from the light exit surface using a light guide plate 45 such as acrylic resin. Also in the light, as in FIG. 2, the inner portion of the optical sheet 30 is pressed by the distal end portion 25 a in the frame inner direction of the fixture 25, and the distal end portion 25 b of the fixture 25 in the frame outer direction is The light chassis 21 is inserted into a groove 27 provided at the peripheral edge. Thereby, the same effect can be produced.

It is a perspective view which shows the external appearance of the liquid crystal display device which concerns on this invention. It is sectional drawing which shows the internal structure of the liquid crystal display device which concerns on this invention. It is a figure which shows the state at the time of the thermal expansion of the optical sheet in the liquid crystal display device which concerns on this invention. It is explanatory drawing which shows the optical sheet attachment method which concerns on this invention. It is sectional drawing which shows the other internal structure of the liquid crystal display device which concerns on this invention. It is sectional drawing which shows the attachment state of the conventional optical sheet.

Explanation of symbols

10 liquid crystal panel 20 backlight 21 backlight chassis 25 mounting portion 25a tip portion (tip portion in the frame inner direction)
25b Tip (tip on the outside of the frame)
27 Groove 30 Optical sheet 40 CCFL

Claims (4)

In a liquid crystal display device comprising a liquid crystal panel and a backlight having one or more light sources on the back of the liquid crystal panel,
An optical sheet provided in a gap between the liquid crystal panel and the backlight, and a peripheral edge thereof is bent toward the backlight;
A liquid crystal display device comprising: a fixture that presses a portion inside the peripheral portion of the bent optical sheet and is fixed to the peripheral portion of the backlight. The fixture has a frame shape corresponding to the peripheral edge of the optical sheet, the front end in the frame inner direction is bent toward the backlight side, and the front end presses the portion inside the peripheral edge of the optical sheet. The liquid crystal display device according to claim 1, wherein the liquid crystal display device is a liquid crystal display device. The light source is provided in a rectangular parallelepiped box having an opening on the liquid crystal panel side and a groove on the edge of the opening side of the two opposing side walls,
3. The liquid crystal display device according to claim 2, wherein the fixing tool has a front end portion bent toward a backlight side and the front end portion is inserted into the groove. In an optical sheet mounting method for mounting an optical sheet on a surface of a backlight having one or more light sources by using a fixture,
Bending the peripheral edge of the optical sheet,
Arrange the optical sheet so that the bent peripheral edge is in contact with the surface of the backlight,
A method of attaching an optical sheet, comprising: pressing an inner portion of the bent optical sheet from the peripheral edge with the fixture, and fixing the fixture to the backlight so as to hold the pressed state.

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